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Bolt vs fx: Features, Pricing & Which Is Better (2026)

A side-by-side comparison of Bolt and fx — features, pricing, and ideal use cases — to help you decide which AI tool fits your workflow.

Bolt logo

Bolt

StackBlitz

Freemium

In-browser AI-powered development agent to prompt, run, edit, and deploy full‑stack websites, apps and prototypes without local setup.

Key features

  • Prompt-Driven Development: Use natural-language prompts to generate, modify, and extend full‑stack application code, accelerating iteration from idea to running prototype.
  • In-Browser Runtime (WebContainers): Run backend and frontend code directly in the browser via StackBlitz WebContainers, eliminating local setup and ensuring generated projects execute immediately.
  • Edit and Live-Preview: Interactive editing of generated code with immediate live previews so developers can refine UI, logic, and configuration in real time.
  • One-Click Deployments: Deploy projects created in Bolt to run on StackBlitz infrastructure (or compatible StackBlitz runtimes) with minimal configuration.
  • Token & Project Management: Built-in usage controls for AI tokens and project visibility, including paid subscription options to increase token allowances and enable private projects.
  • Open-Source DIY Variant: bolt.diy lets users self-host or run an open-source version that permits selecting the LLM for each prompt for customization and privacy.
  • Seamless StackBlitz Compatibility: Any project that runs on StackBlitz will run on Bolt.new, enabling reuse of StackBlitz templates, examples, and ecosystems.
  • Prompt-driven generation of full-stack applications and prototypes
  • In-browser runtime and editing powered by StackBlitz WebContainers (no local setup)
  • Run, test, and iterate on generated code immediately in the browser
  • Deploy full-stack applications from the browser
  • Paid subscription option for additional AI tokens and private projects
  • Open-source variant (bolt.diy) enabling selection of custom LLMs per prompt
  • Seamless compatibility with projects that run on StackBlitz

Best for

  • Rapid Prototyping: Quickly generate and iterate on web app prototypes by prompting Bolt to scaffold frontend and backend code and preview instant results in the browser.
  • Full-Stack Development Without Setup: Build, test, and run full‑stack applications in environments where installing local toolchains is impractical (e.g., workshops, classrooms, demos).
  • Demo and Portfolio Deployments: Create and deploy interactive demos or portfolio projects quickly for stakeholder reviews or user testing without managing servers.
  • Custom LLM Workflows (bolt.diy): Teams that require specific LLMs or on‑premise models can use the open-source bolt.diy to route prompts to chosen models and preserve data control.
  • Learning and Teaching: Instructors and learners can use Bolt to demonstrate full‑stack concepts, generate example code, and explore modifications live during lessons.
  • Accelerating Feature Development: Developers can use Bolt to scaffold features, generate boilerplate, and then refine the generated code manually to speed up development cycles.
  • Rapid prototyping of web apps and front-to-back demos directly in the browser
  • Learning and teaching web development with immediate runnable examples
  • Building and iterating on UI/UX prototypes without local environment setup
  • Generating starting codebases or feature scaffolds using natural language prompts
  • Creating private projects and increasing AI usage via paid subscription
View Bolt details
fx logo

fx

Vercel Labs

Free

Vercel Labs' tiny open-source coding agent — a ~6 MB native CLI written in Zig, built for speed, embeddability and Unix-style ergonomics.

Key features

  • Tiny Native Binary: The whole agent ships as a roughly 6 MB executable designed for instant installation and for embedding in resource-constrained environments and agent sandboxes.
  • Instant Time to Prompt: fx cold starts in about 10 microseconds and performs no unnecessary work or I/O before accepting user input, which matters for programmatic invocation.
  • Minimal Memory Footprint: A single-digit-megabyte memory baseline lets you pack many concurrent instances onto one machine.
  • Shell-Like Ergonomics: Scroll history is preserved by default and output is deliberately sparse, so the CLI composes like a Unix tool instead of taking over the terminal.
  • Context Efficiency: A minimal system prompt and tool surface reduce token spend and improve time-to-first-token performance.
  • WebAssembly Builds: Optimal fx.wasm builds from the Zig toolchain shrink the binary further and make the network stack pluggable, enabling the in-browser demo.
  • Model and Provider Agnostic: Works with local models, LLM gateways, direct provider API access or existing subscriptions rather than locking you to one vendor.
  • Extensible Small Core: Capabilities are added through skills, plugins and MCPs, following a Unix-like philosophy of a small core with composable extensions.

Best for

  • Sandboxed Agent Execution: Ship a full coding agent inside a container or sandbox where a large runtime would not fit.
  • Embedding in Larger Systems: Use fx as the agent harness inside your own product or internal platform rather than building a loop from scratch.
  • CI and Scripted Automation: Invoke a coding agent from pipelines and scripts where fast cold starts and quiet output matter more than an interactive UI.
  • Agent Harness Research: Experiment with system prompt and tool design on a deliberately minimal, readable Apache-2.0 codebase.
  • Local-Model Coding: Run agentic coding against a locally hosted model without any dependency on a specific cloud provider.
  • Browser-Based Demos and Playgrounds: Compile to WebAssembly and run the agent client-side with networking delegated to browser fetch.
View fx details